There are 24 types of BT tool holders. Commonly used ones are: BT-SK High Speed Tool Holder, BT-GER High Speed Tool Holder, BT-ER Elastic Tool Holder, BT-C Powerful Tool Holder, BT-APU Integrated Drill Chuck, BT -FMA Face Milling Tool Holder, BT-FMB-Face Milling Tool Holder, BT-SCA Side Milling Tool Holder, BT-SLA Side Milling Tool Holder, BT-MTA Morse Drill Holder, BT-MTB Morse Taper Tool Holder, BT Oil Path Tool Holder, BT-SDC Back Pull Type Tool Holder.